X-ray tube.



E. THOMSON.

X-RAY TUBE.

APPLICATION FILED SEPT. 14, 1914.

l 1 9%,?6, Patented Jul 25, 1916.

Witnesses: lnvehtor; fggg 46% b Elihu Thomsop ELIH'U THOMSON, Q1 LYNN,MASSACHUSETTS, ASSIGNOR T GEHEEMQFQELEGTH-IO CGMPANY, CGEPQRA'IION OFNEW YORK.

X-nsr time.

1,192,?(36, specification To all whom it may concern:

Be it known that l, Enrrro TiioMsoN, e citizen of the United States,residing at Lynn, county of Essex, State of Massachusetts, have inventedcertain new and useful Improvements in Iii-Rey Tubes, of which thefollowing is a description.

The present invention relates to K rey devicesand its object is toprevent locel overheetin end melting of the metal on the surface or eterget or electrode subjected to the bombardment of cathode rays inaccordance with my invention overheating of focal spot, the port of thesurface of the target or unticetiiode subjected to the borr nrdnient ofthe cathode rays is prevented by successively renewing the tergetsurfece during the operation of the tube,'for exempie, by making the teret in the shape of t'lleti or disk and rotating the same any W y, forexample, by externel means or by the reaction of the rays striking *1 mmof the tar tangentially. The of y invention are pointed on particularityin the epper inv reference in conneo ings in Wli Figure I. a, rotatablethe cetliode with greet claims derstood by e foliowing description taken:2 accompanying drewolved by the impact of 2 is e deteii pien View ofthe rote .et; 3 is side elevetion of Le terg-et partly in section; Fina4c is e deti form of et; Fig, 5 shows in outline an X-rey tube w ing theerg-st roteted by externei. men and Fig. is o deteii sectional view of ecetnode operebie at incendescence in a highly evacuated tube in "which.the cathode or bets rays ere produced by pure electron emission Theiii-ray tube shown in Fig. 1 consists as'usuel 2, glass envelop 1 havingside arms 2, 3, into the stem 4, 5 of which are respectively sealed thecathode conductor 6 end the anode conductor 7. The cathode 8 which mayconsist of aluminum is of the usuei concuve or dished type proportionedto focus the cathode rays upon limited surface area of the target. Thetergetfi is fashioned in the shape of ewbeel so posi= tioned by means ofthe carriers 10 that the es cathode rays Will be directed tengentiellyto tube containing ed sectionel View of e modified I to rotate thetarget I may, as shown Y ofletfirs Patent Eetented July 25, idltdoApplication filed eeptember 14, 191%. Serial No. 881,519. I

its surface so as to produce rotation in the .d rection of the arrow.Although the sotwo surface upon which the cathode rays are received isthereby continuously renewed the X-rays as shown by dotted lines arecontinuously directed downwardly es the relative position-of the cbtbodespot remains the same. As the surface of the terget has aregularlcontour, as indicated in the drawing, the position of thecathode spot remains substentieily fixed in space and, therefore, theX-reys are continuously emitted and the direction of the rays withrespect to the object to be treated or exemined remains substantiallythe some.

The Wheel 9, as shown in Figs 2 and 3, may consist of a frame Work ofcopper or like metal of good beet conductivity comprising a hub 11 andoutwardly extending spoxes 12 between the flared ends of which areis-pinched or otherwise joined a perip ierui band 13 of tungsten, orother ii refrestory metal. The shaft i ire & liite bearings 15 so as togive iubricen and enable the Wheel when carefully beienced to be easilyro' ed anothe co struction, shown in i, e eripheral merit-13 of tungstenor the like is inc by tWo thin disks 16, 16, of Copper 0'; law metal,these disks beii eld toge her smell rivets 17 as indies e The tungstenor refractory 331% in Figs. 3 4 need not be e; comp etout to ailow forexpansion on been it can be composed llnsteed of depending upon acomponent of the repulsive of the cathode 5, rotate the target by menetic zneens, target 9 is connected Wi e inetel supported by one end onthe same bearing" es the target and ot the other end upon beering 20 ina, side arm 21 of the tube. Upon this rod 19 in tire side is mounted amagnetic member 22 which it the simpiest form may be e small red iron.Immediately outside of the side '21 is a rotating magnet 23, the poles2e, 25

of which are closely adj ecentto the megnetio member 22. By rotetingthismegnetupon 'a shaft 26 in any convenient manner the target 9 may berotated at anydesired speed. Of course instead of using a rotatingmagnet, a rotating magnetic field may be pro duced by other convenientmeans. Both Figs. 1 and 5 show an X-ray tube having an unheated targetand therefore contain a small amount of gas and operate by positiveionization, but my invention is easily applicable to a tube containingan incandescent cathode 27, as shown in Fig. 6, surrounded by focusingmember 28, the

' vacuum in the tube being so high that positive ionization issubstantially absent and the cathode rays being produced bysubstantially pure electron emission from the heated cathode.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is 1. Themethod of increasing the capacity 7 of an X-ray tubewhich consists in directing cathode rays upon a limited area of thesurface of a refractory target and renewing 4. An X-ray tube comprisingan envelop,

means for generating cathode rays and a rotatable anti-cathodecomprising a circular band of tungsten.

5. In an X-ray device, the combination of means for producing cathoderays, a target comprising a band of refractoryv metal upon which saidrays impinge, and means movably supfporting said target to permit achange 0 surface subjected tothe bombardment of the cathode rays.

6. In an X-ray device the combination of means for producing aconverging bundle of cathode rays, a refractory target of regularcontour located near the focus of said rays, and means movablysupporting said target in a position to permit motion of said target bythe impact of said cathode rays. 7. In an X-ray device, the combinationof a rotatable refractory target of regular contour, a mountingtherefor, and means for directing a stream of cathode rays tangentiallyupon said target.

8. An X-ray device, comprising the combination of means for generatingcathode rays, a target surface located in the path of Said rays andmeans for changing the target surface receiving said rays while saidrays are impinging on said target.

In witness whereof, I have hereunto set my hand this eighth day ofSeptember, 1914.

ELIHU THOMSON.

. Witnesses:v

JOHN. A. MoMANUs, 'Jr., FRANK Gr. HAT'IIE.

